Hard dental tissue having suffered large damage due to dental caries or the like, is conventionally restored by a procedure in which an indirect restoration such as a crown, a bridge, an inlay, or an onlay, is adhered on the damaged portion of the hard dental tissue with a specific dental composition such as a dental resin cement. Conventionally, a primer is required as a pre-treatment agent in order to improve adhesion of the resin cement to the dental hard tissue.
Alternatively, damaged hard dental tissue may be restored by using a direct restorative material which is applied as an uncured dental composition such as a dental composite, and hardened. Also in case of a dental composite, a primer is often required as a pre-treatment agent in order to improve adhesion of the dental composite to the dental hard tissue.
A dental resin cement and a dental composite are required to have sufficient adhesive and a material strength. Otherwise, not only the dental composition may be released from the hard dental tissue after some time under the severe conditions of the oral environment, but also a gap may be produced at an interface between the dental composition and the teeth, and bacteria may invade onto the exposed surfaces and impose an adverse effect on dental pulp.
The dental hard tissue is composed of enamel and dentin, and adhesion of the dental composition to both of them is clinically required. The primer for pre-treating a tooth surface has been conventionally used prior to application of a dental restorative composition for enhancing adhesion by demineralizing the tooth surface for making it rough and facilitating infiltration of the resin into a fine rough surface. Accordingly, when the dental composition is cured by chemical polymerization or photopolymerization, the adhesion to the hard dental tissue may be improved.
Given that the use of a dental primer increases the complexity of a dental procedure, a simple adhesion procedure is desired which uses a self-adhesive dental composition which does not require a primer treatment for such various adherends.
Moreover, since adhesion of a dental composition to hard dental tissue requires the presence of acidic groups in the composition, the dental composition desireably has a high hydrolysis stability in order to avoid degradation of the composition during storage or when applied to hard dental tissue.
Japanese Patent Publication No. 2006-512466A discloses a self-adhesive resin cement which does not require the primer, that is a polymerizable composite material comprising at least one multifunctional monomer containing an acid in a concentration range of about 10-85% by weight, a non-reactive filler in a concentration range of about 1-80% by weight, a polymerization system in a concentration range of about 1.5-25% by weight, and water in a concentration range of about 0.1-25% by weight. However, since such the composition uses a single acidic monomer, sufficient adherability cannot be attained for both of inorganic component-rich enamel and organic component- and water-rich dentin.
International Publication No. WO 02/092021A1 discloses a self-adhesive dental composition consisting of a liquid and a powder. The resin cement consisting of the liquid and the powder, i.e. a powder-liquid type resin cement, is inferior in manipulability upon mixing as compared with a paste-and-paste type resin cement.
Japanese Patent Publication No. 2005-65902A discloses a dental adhesive composition comprising, as an essential adhesive component, a carboxylic acid compound having one (meth)acryloyl group and one carboxyl group which are bound to an aromatic group as a polymerizable monomer containing a particular carboxylic acid group. However, such the polymerizable monomer having an ester group quickly degrades in an acidic medium.
Dental materials based on polyfunctional amides are known from U.S. Pat. No. 6,953,832 which contain specific polymerizable amides and optionally strongly acidic polymerizable monomers such as dipentaerythritol pentamethacryloyloxy dihydrogenphosphate. Filler containing compositions are suggested. However, U.S. Pat. No. 6,953,832 does not disclose a self-adhesive composite.
WO92/21632 discloses a mixture of the following isomers of an ethylenically-unsaturated acidic alkoxysilane H2C═C(COOH)CH2C(O)NH(CH2)3Si(OC2H5)3 and H2C═C(CH2COOH)C(O)NH(CH2)3Si(OC2H5)3. The mixture is hydrolysed in a treatment solution further containing ethanol and water for treating the surface of a glass powder. The surface treated glass powder is used in a cement composition. Therefore, WO92/21632 neither discloses a hydrolysis-stable ethylenically-unsaturated monomer nor a dental composition comprising a particulate filler and a polymerizable hydrolysis-stable ethylenically-unsaturated monomer.
WO2008/121895 discloses a compound of the following formula:
wherein, the Rs in each n monomer are independently selected from the group consisting of hydrogen, (C1-C6) alkyl, (C2-C6) alkenyl, (C2-C6) alkynyl, (C6-C10) aryl (C1-C6) alkyl and (CH2)2SCH3; R4 is independently selected from the group consisting of (C2-C20) alkylene, (C2-C20) alkenylene, (C2-C8) alkyloxy (C2-C20) alkylene, bicyclic-fragments of 1,4:3,6-dianhydrohexitols, and combinations thereof; and R7 is independently selected from the group consisting of —CH═CH2, —C(CH3)═CH2, —CH═CH—(C6H5), and —CH═CH—COOH. These compounds cannot be considered to be hydrolysis-stable given the ester groups essentially present in the molecule.